1. Field of the Invention
The present invention relates to a new type of material that employs diamond to enhance its physical properties. More specifically, the present invention relates to an open-cell reticulated structure coated into and throughout with a diamond material and at least partially filled with another material.
2. The Prior Art
There is a broad class of known materials classed as open-cell foams. These materials consist of reticulated structures through which fluids can flow. They resemble the intersections observed in a mass of bubbles, hence their description as xe2x80x9cfoamxe2x80x9d.
These materials can be fabricated by a variety of methods, and are available in various ceramics, metals, and carbon. These materials exhibit a three-dimensional reticulated unitary structure, which distinguishes them from other open-cell structures, such as stacked screens, comprising the mechanical juxtaposition of otherwise separate components.
These materials find a variety of uses in industry. For example, foams made of silicon carbide can be used to filter slag from molten aluminum. In other applications, fluid flows through a foam structure to carry away or supply heat. In this use, the inherent high surface area to volume ratio of the foam provides superior heat transport compared to planar heat exchangers.
Diamond/nondiamond composite materials formed by chemical vapor infiltration are also known in the art. Examples of such materials are found in U.S. Pat. No. 5,609,955 and U.S. Pat. No. 5,614,140. These materials are formed by consolidation of particulate substrate materials with diamond deposited through chemical vapor infiltration processes. These materials often contain residual porosity, or voids, that remain due to the blockage of diffusion channels that supply activated gas species to the interior. These voids degrade the material""s bulk thermal conductivity and can act as stress concentrators to reduce breakage resistance. These residual porosities or voids are often closed off from the external environment and therefore cannot play any role in supporting fluid flow through the consolidated composite material.
These materials are distinct from the present invention in that they are formed by fusion of a multiplicity of separate particles into a single resultant structure, whereas the instant invention coats an existing unitary structure with diamond.
The present invention is diamond foam, and methods for its manufacture, consisting of diamond deposited on a pre-existing framework, the framework being compatible with diamond deposition, and having an open-cell structure. Subsequent to diamond deposition, the diamond-coated framework is at least partially filled with, and/or coated with another material.
A method for forming a diamond foam according to the present invention comprises providing a substrate; preparing the substrate for diamond deposition; depositing diamond or doped diamond material on the substrate; followed by partial or complete infiltration and/or coating of the diamond material with another material. According to the present invention, the diamond material can be deposited on the substrate by one of several diamond deposition methods.